Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100005825/jz1398sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270100005825/jz1398Isup2.hkl |
CCDC reference: 147628
The title compound was prepared as described by Popović et al. (1999). Crystals suitable for X-ray analysis were formed from a very dilute methanol solution at room temperature on standing for several days.
The registered intensity data consisted of two octants and included a full set of Friedel opposites. Methyl H atoms were identified from difference syntheses, idealized and the rigid methyl groups allowed to rotate but not tip. Other H atoms were included at calculated positions and refined using a riding model; the H-atom isotropic displacement parameters were kept equal to 1.5Ueq for Csp3, and 1.2 for for Csp2. The H atoms at N12 and N22 could be tentatively identified in the different Fourier map, but were not well defined. They were therefore generated assuming sp2 hybridization at N and refined with a riding model. The polar axis direction was determined unambiguously by refining the Flack parameter. The maximum and minimum electron-density peaks in the final difference Fourier map are located 0.71 and 0.86 Å, respectively, from the Hg atom.
Data collection: STADI4 (Stoe & Cie, 1995); cell refinement: STADI4; data reduction: X-RED (Stoe & Cie, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON98 (Spek, 1998); software used to prepare material for publication: SHELXL97.
[HgI2(C4H6N2)2] | F(000) = 1224 |
Mr = 682.73 | Dx = 2.830 Mg m−3 |
Orthorhombic, Pca21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2c -2ac | Cell parameters from 33 reflections |
a = 11.543 (2) Å | θ = 10.0–18.6° |
b = 13.996 (5) Å | µ = 13.71 mm−1 |
c = 9.9180 (7) Å | T = 293 K |
V = 1602.3 (7) Å3 | Plate, colourless |
Z = 4 | 0.70 × 0.38 × 0.05 mm |
Philips PW1100 diffractometer updated by Stoe | 3590 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.060 |
Graphite monochromator | θmax = 30.0°, θmin = 3.1° |
ω scans | h = −16→16 |
Absorption correction: integration (X-RED; Stoe & Cie, 1995) | k = −19→19 |
Tmin = 0.074, Tmax = 0.505 | l = −13→13 |
5113 measured reflections | 5 standard reflections every 90 min |
4575 independent reflections | intensity decay: 6.4% |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.043 | H-atom parameters constrained |
wR(F2) = 0.116 | Calculated w = 1/[σ2(Fo2) + (0.0793P)2 + 0.3812P] where P = (Fo2 + 2Fc2)/3 |
S = 1.02 | (Δ/σ)max < 0.001 |
4575 reflections | Δρmax = 0.99 e Å−3 |
156 parameters | Δρmin = −1.45 e Å−3 |
1 restraint | Absolute structure: Flack (1983) |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.007 (8); 2110 Friedel pairs |
[HgI2(C4H6N2)2] | V = 1602.3 (7) Å3 |
Mr = 682.73 | Z = 4 |
Orthorhombic, Pca21 | Mo Kα radiation |
a = 11.543 (2) Å | µ = 13.71 mm−1 |
b = 13.996 (5) Å | T = 293 K |
c = 9.9180 (7) Å | 0.70 × 0.38 × 0.05 mm |
Philips PW1100 diffractometer updated by Stoe | 3590 reflections with I > 2σ(I) |
Absorption correction: integration (X-RED; Stoe & Cie, 1995) | Rint = 0.060 |
Tmin = 0.074, Tmax = 0.505 | 5 standard reflections every 90 min |
5113 measured reflections | intensity decay: 6.4% |
4575 independent reflections |
R[F2 > 2σ(F2)] = 0.043 | H-atom parameters constrained |
wR(F2) = 0.116 | Δρmax = 0.99 e Å−3 |
S = 1.02 | Δρmin = −1.45 e Å−3 |
4575 reflections | Absolute structure: Flack (1983) |
156 parameters | Absolute structure parameter: −0.007 (8); 2110 Friedel pairs |
1 restraint |
Experimental. The Gaussian absorption correction was based on the following indexed crystal faces and distances in mm: 010 0.1349, 0–10 0.1349, 001 0.025, 00–1 0.025, 111 0.2475, −100 0.3479, 100 0.3479. |
x | y | z | Uiso*/Ueq | ||
Hg | −0.05011 (3) | 0.26093 (3) | 0.85625 (7) | 0.04622 (11) | |
I1 | −0.15470 (5) | 0.16607 (5) | 0.64205 (6) | 0.04358 (15) | |
I2 | 0.16215 (5) | 0.34169 (5) | 0.78087 (6) | 0.04754 (17) | |
S1 | −0.16820 (19) | 0.3940 (2) | 0.9583 (3) | 0.0466 (6) | |
N11 | −0.4003 (6) | 0.4140 (6) | 0.9777 (7) | 0.0375 (15) | |
N12 | −0.3524 (6) | 0.3223 (6) | 0.8150 (8) | 0.0437 (19) | |
H12N | −0.3123 | 0.2905 | 0.7573 | 0.052* | |
C11 | −0.3090 (7) | 0.3749 (6) | 0.9167 (9) | 0.0345 (16) | |
C12 | −0.5028 (8) | 0.3865 (8) | 0.9161 (11) | 0.047 (2) | |
H12 | −0.5774 | 0.4058 | 0.9391 | 0.057* | |
C13 | −0.4734 (9) | 0.3277 (9) | 0.8185 (11) | 0.052 (3) | |
H13 | −0.5241 | 0.2954 | 0.7617 | 0.063* | |
C14 | −0.3928 (9) | 0.4802 (8) | 1.0916 (10) | 0.048 (2) | |
H14A | −0.3328 | 0.4596 | 1.1520 | 0.072* | |
H14B | −0.4655 | 0.4814 | 1.1385 | 0.072* | |
H14C | −0.3751 | 0.5432 | 1.0590 | 0.072* | |
S2 | 0.0049 (2) | 0.14267 (19) | 1.0447 (3) | 0.0444 (5) | |
N21 | 0.1810 (6) | 0.0621 (6) | 0.8988 (8) | 0.0406 (17) | |
N22 | 0.2403 (7) | 0.1622 (6) | 1.0452 (9) | 0.049 (2) | |
H22N | 0.2414 | 0.2040 | 1.1088 | 0.058* | |
C21 | 0.1458 (7) | 0.1213 (7) | 0.9962 (9) | 0.0358 (16) | |
C22 | 0.2987 (8) | 0.0658 (9) | 0.8913 (11) | 0.055 (3) | |
H22 | 0.3442 | 0.0297 | 0.8331 | 0.066* | |
C23 | 0.3377 (9) | 0.1276 (10) | 0.9784 (16) | 0.068 (4) | |
H23 | 0.4144 | 0.1450 | 0.9929 | 0.081* | |
C24 | 0.1079 (8) | 0.0009 (10) | 0.8170 (13) | 0.061 (3) | |
H24A | 0.0287 | 0.0210 | 0.8253 | 0.091* | |
H24B | 0.1151 | −0.0640 | 0.8472 | 0.091* | |
H24C | 0.1314 | 0.0052 | 0.7243 | 0.091* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Hg | 0.03560 (16) | 0.0487 (2) | 0.0544 (2) | 0.00502 (13) | 0.00110 (18) | 0.0010 (2) |
I1 | 0.0407 (3) | 0.0457 (3) | 0.0444 (3) | 0.0018 (2) | 0.0026 (2) | −0.0027 (3) |
I2 | 0.0361 (3) | 0.0533 (4) | 0.0533 (4) | −0.0048 (2) | 0.0075 (3) | −0.0049 (3) |
S1 | 0.0317 (10) | 0.0465 (14) | 0.0615 (15) | −0.0013 (9) | 0.0007 (9) | −0.0093 (11) |
N11 | 0.040 (4) | 0.041 (4) | 0.032 (3) | 0.005 (3) | 0.008 (3) | 0.000 (3) |
N12 | 0.043 (4) | 0.048 (5) | 0.040 (4) | 0.006 (3) | 0.003 (3) | −0.021 (3) |
C11 | 0.036 (4) | 0.031 (4) | 0.036 (4) | 0.009 (3) | −0.002 (3) | 0.001 (3) |
C12 | 0.033 (4) | 0.049 (5) | 0.059 (5) | 0.020 (4) | 0.000 (4) | −0.001 (5) |
C13 | 0.037 (4) | 0.071 (8) | 0.049 (6) | 0.000 (4) | −0.007 (4) | −0.013 (5) |
C14 | 0.052 (5) | 0.052 (6) | 0.040 (5) | 0.006 (4) | 0.008 (4) | −0.005 (4) |
S2 | 0.0427 (11) | 0.0500 (13) | 0.0406 (11) | 0.0046 (10) | 0.0088 (10) | 0.0046 (10) |
N21 | 0.026 (3) | 0.046 (4) | 0.050 (4) | 0.005 (3) | −0.003 (3) | −0.008 (3) |
N22 | 0.040 (4) | 0.056 (5) | 0.050 (5) | 0.006 (4) | −0.009 (4) | −0.011 (4) |
C21 | 0.035 (4) | 0.037 (4) | 0.035 (4) | 0.005 (3) | −0.002 (3) | −0.003 (3) |
C22 | 0.026 (4) | 0.078 (8) | 0.061 (7) | 0.009 (4) | −0.012 (4) | −0.016 (5) |
C23 | 0.040 (5) | 0.064 (8) | 0.098 (11) | 0.008 (5) | −0.016 (6) | −0.020 (8) |
C24 | 0.041 (5) | 0.070 (7) | 0.071 (7) | 0.002 (5) | 0.007 (5) | −0.028 (6) |
Hg—S1 | 2.520 (3) | N22—C21 | 1.325 (12) |
Hg—S2 | 2.576 (3) | N22—C23 | 1.391 (15) |
Hg—I1 | 2.7809 (9) | C22—C23 | 1.302 (17) |
Hg—I2 | 2.7999 (8) | N12—H12N | 0.86 |
S1—C11 | 1.698 (9) | C12—H12 | 0.93 |
N11—C11 | 1.333 (11) | C13—H13 | 0.93 |
N11—C12 | 1.387 (13) | C14—H14A | 0.96 |
N11—C14 | 1.463 (12) | C14—H14B | 0.96 |
N12—C11 | 1.345 (12) | C14—H14C | 0.96 |
N12—C13 | 1.399 (12) | N22—H22N | 0.86 |
C12—C13 | 1.316 (15) | C22—H22 | 0.93 |
S2—C21 | 1.721 (9) | C23—H23 | 0.93 |
N21—C21 | 1.335 (12) | C24—H24A | 0.96 |
N21—C22 | 1.361 (10) | C24—H24B | 0.96 |
N21—C24 | 1.452 (13) | C24—H24C | 0.96 |
S1—Hg—S2 | 108.49 (9) | C22—C23—N22 | 105.5 (10) |
S1—Hg—I1 | 115.14 (6) | C11—N12—H12N | 125.6 |
S2—Hg—I1 | 110.76 (7) | C13—N12—H12N | 125.6 |
S1—Hg—I2 | 106.39 (6) | C13—C12—H12 | 126.9 |
S2—Hg—I2 | 103.72 (6) | N11—C12—H12 | 126.9 |
I1—Hg—I2 | 111.63 (3) | C12—C13—H13 | 126.0 |
C11—S1—Hg | 107.7 (3) | N12—C13—H13 | 126.0 |
C11—N11—C12 | 111.1 (8) | N11—C14—H14A | 109.5 |
C11—N11—C14 | 124.3 (8) | N11—C14—H14B | 109.5 |
C12—N11—C14 | 124.5 (8) | H14A—C14—H14B | 109.5 |
C11—N12—C13 | 108.9 (8) | N11—C14—H14C | 109.5 |
N11—C11—N12 | 105.7 (8) | H14A—C14—H14C | 109.5 |
N11—C11—S1 | 125.6 (7) | H14B—C14—H14C | 109.5 |
N12—C11—S1 | 128.7 (7) | C21—N22—H22N | 125.1 |
C13—C12—N11 | 106.1 (8) | C23—N22—H22N | 125.1 |
C12—C13—N12 | 108.1 (9) | C23—C22—H22 | 125.3 |
C21—S2—Hg | 98.2 (3) | N21—C22—H22 | 125.3 |
C21—N21—C22 | 108.7 (8) | C22—C23—H23 | 127.2 |
C21—N21—C24 | 126.4 (7) | N22—C23—H23 | 127.2 |
C22—N21—C24 | 124.9 (9) | N21—C24—H24A | 109.5 |
C21—N22—C23 | 109.9 (9) | N21—C24—H24B | 109.5 |
N22—C21—N21 | 106.4 (8) | H24A—C24—H24B | 109.5 |
N22—C21—S2 | 126.9 (7) | N21—C24—H24C | 109.5 |
N21—C21—S2 | 126.7 (7) | H24A—C24—H24C | 109.5 |
C23—C22—N21 | 109.5 (10) | H24B—C24—H24C | 109.5 |
S2—Hg—S1—C11 | −103.7 (3) | S1—Hg—S2—C21 | −138.8 (3) |
I1—Hg—S1—C11 | 21.0 (4) | I1—Hg—S2—C21 | 93.9 (3) |
I2—Hg—S1—C11 | 145.2 (3) | I2—Hg—S2—C21 | −26.0 (3) |
C12—N11—C11—N12 | 0.3 (10) | C23—N22—C21—N21 | −0.6 (12) |
C14—N11—C11—N12 | −177.5 (9) | C23—N22—C21—S2 | −178.8 (10) |
C12—N11—C11—S1 | 177.7 (7) | C22—N21—C21—N22 | 1.5 (12) |
C14—N11—C11—S1 | −0.1 (13) | C24—N21—C21—N22 | 179.3 (11) |
C13—N12—C11—N11 | −2.1 (11) | C22—N21—C21—S2 | 179.7 (8) |
C13—N12—C11—S1 | −179.4 (8) | C24—N21—C21—S2 | −2.5 (16) |
Hg—S1—C11—N11 | 162.0 (7) | Hg—S2—C21—N22 | 97.7 (9) |
Hg—S1—C11—N12 | −21.2 (10) | Hg—S2—C21—N21 | −80.1 (9) |
C11—N11—C12—C13 | 1.7 (12) | C21—N21—C22—C23 | −1.9 (16) |
C14—N11—C12—C13 | 179.5 (10) | C24—N21—C22—C23 | −179.8 (12) |
N11—C12—C13—N12 | −2.9 (14) | N21—C22—C23—N22 | 1.5 (16) |
C11—N12—C13—C12 | 3.2 (14) | C21—N22—C23—C22 | −0.5 (15) |
D—H···A | D—H | H···A | D···A | D—H···A |
N12—H12N···I1 | 0.86 | 2.77 | 3.596 (8) | 163 |
N22—H22N···I2i | 0.86 | 2.80 | 3.611 (9) | 157 |
Symmetry code: (i) −x+1/2, y, z+1/2. |
Experimental details
Crystal data | |
Chemical formula | [HgI2(C4H6N2)2] |
Mr | 682.73 |
Crystal system, space group | Orthorhombic, Pca21 |
Temperature (K) | 293 |
a, b, c (Å) | 11.543 (2), 13.996 (5), 9.9180 (7) |
V (Å3) | 1602.3 (7) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 13.71 |
Crystal size (mm) | 0.70 × 0.38 × 0.05 |
Data collection | |
Diffractometer | Philips PW1100 diffractometer updated by Stoe |
Absorption correction | Integration (X-RED; Stoe & Cie, 1995) |
Tmin, Tmax | 0.074, 0.505 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5113, 4575, 3590 |
Rint | 0.060 |
(sin θ/λ)max (Å−1) | 0.703 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.043, 0.116, 1.02 |
No. of reflections | 4575 |
No. of parameters | 156 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.99, −1.45 |
Absolute structure | Flack (1983) |
Absolute structure parameter | −0.007 (8); 2110 Friedel pairs |
Computer programs: STADI4 (Stoe & Cie, 1995), STADI4, X-RED (Stoe & Cie, 1995), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), PLATON98 (Spek, 1998), SHELXL97.
Hg—S1 | 2.520 (3) | N11—C12 | 1.387 (13) |
Hg—S2 | 2.576 (3) | N12—C11 | 1.345 (12) |
Hg—I1 | 2.7809 (9) | S2—C21 | 1.721 (9) |
Hg—I2 | 2.7999 (8) | N21—C21 | 1.335 (12) |
S1—C11 | 1.698 (9) | N21—C22 | 1.361 (10) |
N11—C11 | 1.333 (11) | N22—C21 | 1.325 (12) |
S1—Hg—S2 | 108.49 (9) | S1—Hg—I2 | 106.39 (6) |
S1—Hg—I1 | 115.14 (6) | S2—Hg—I2 | 103.72 (6) |
S2—Hg—I1 | 110.76 (7) | I1—Hg—I2 | 111.63 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
N12—H12N···I1 | 0.86 | 2.77 | 3.596 (8) | 163 |
N22—H22N···I2i | 0.86 | 2.80 | 3.611 (9) | 157 |
Symmetry code: (i) −x+1/2, y, z+1/2. |
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Heterocyclic thionates are electron-rich polyfunctional ligands (Raper, 1996). Whereas heterocyclic thionates are ambidentate ligands (S– or N-donor atoms), their monosubstituted analogues are S,N-bridging and/or chelating ligands. The N-disubstituted derivatives are exclusively monodentate S donors. Currently available X-ray structural data show that 1-methyl-1,3-imidazole-2-thione (meimtH) can act as a neutral S-donor ligand (Raper & Nowell, 1979, 1980; García-Martínez et al., 1993; Raper et al., 1980; Nowell et al., 1974; Raper & Brooks, 1977; Birker et al., 1982; O'Neill et al., 1982), as an S-bridging ligand (Creighton et al., 1985; Raper & Clegg, 1991) or as an anionic ligand (S-donor: Norris et al., 1983; N,S-bridging: Cooper et al., 1986; Raper et al., 1991; Agnus et al., 1980; Castro et al., 1995; Popović et al., 1999). The structure of the ligand itself, i.e. 1-methyl-1,3-imidazole-2-thione (meimtH), is known from two independent studies (Raper et al., 1983; Vampa et al., 1995). The C═S bond distances [1.686 (2) and 1.682 (2) Å in two crystallographically independent molecules; Vampa et al., 1995] and the protonation at N3 establish the presence of the thione tautomer in the solid state.
Mercury(II) halides form 1:1 and 1:2 complexes with 1-methyl-1,3-imidazole-2-thione, HgX2(meimtH) and HgX2(meimtH)2, whereas mercury(II) acetate forms the complex Hg(meimt)2. Two mercury(II) complexes with 1-methyl-1,3-imidazole-2-thione derived from HgBr2 (Raper et al., 1998) and Hg(Oac)2 (Popović et al., 1999) have been structurally examined. Firstly, HgBr2(meimtH) (Raper et al., 1998), with a 4 + 1 trigonal-bipyramidal mercury coordination, contains bromo-bridged dimers that are further linked into weakly associated polymeric sheets via Hg···Br contacts of 3.587–3.791 Å. The monodentate meimtH ligand has thione–sulfur ligating character with Hg—S distances of 2.405 (4)–2.419 (4) Å. Secondly, Hg(meimt)2 (Popović et al., 1999) possesses an Hg atom located on a twofold axis coordinated by two S [2.4305 (12) Å] and two N atoms [2.451 (4) Å] from four meimt ligands. The Hg—N bond is longer than the sum of the covalent radii for N and tetrahedral Hg (2.23 Å; Pauling, 1960; Grdenić, 1965). The Hg—S distance of 2.4305 (12) Å lies between expected values for linear and tetrahedral coordination. The meimt ligands bridge two Hg atoms forming endless chains parallel to the z axis.
The coordination of meimtH towards methylmercurio compounds appears to be dependent on pH and on the molar ratio of reactants. In complexes with a 1:1 mercury-to-meimtH ratio, Hg—S bonds are formed irrespective of the pH of the medium, whereas for the 2:1 ratio in basic conditions, both Hg—S and Hg—N bonds are expected to be formed (Buncel et al., 1982). There are two monomeric complexes containing the CH3HgII unit, which is bonded to the exocyclic sulfur by Hg—S bonds of 2.382 (2) Å in CH3Hg(meimtH)(NO3) and 2.338 (7) Å in CH3Hg(meimt) (Norris et al., 1983). Although the ligand in the latter contains an available electron lone pair at the deprotonated N atom, Hg does not form intermolecular contacts with the N atom of adjacent molecules, and the Hg—S bond distance is equal to the sum of Hg and S covalent radii of 2.34 Å (Grdenić, 1965; Pauling, 1960).
The molecule of the title compound HgI2(meimtH)2 is situated in a general position (Fig. 1). The Hg atom is tetrahedrally coordinated by two I atoms [Hg—I1 2.7809 (9) Å and Hg—I2 2.7999 (8) Å] and two thione S atoms [Hg—S1 2.520 (3) Å and Hg—S2 2.576 (3) Å]. The Hg—I distances are slightly shorter than the sum of covalent radii for I and Hg in tetrahedral coordination (2.81 Å; Pauling, 1960; Grdenić, 1965) and correspond well to the Hg—I distance in the red tetrahedral form of HgI2 [2.783 (3) Å; Jeffrey & Vlasse, 1967]. In contrast, in the 1:1 complex with non-substituted 1,3-imidazole-2-thione, HgI2(imtH2), Hg displays a 3 + 1 coordination and the Hg—I bond values are markedly different [2.8187 (7) and 2.6518 (7) Å; Popović et al., 1999] because of participation of one of the I atoms in dimer formation.
The valence angles around The Hg atom of the title compound, (I), lie in the range 103.72 (6)–115.14 (6)°, corresponding to a somewhat distorted tetrahedral geometry at mercury. The Hg—S bond values are slightly longer than the sum of covalent radii for sulfur and tetrahedrally coordinated mercury (1.04 and 1.48 Å, respectively; Pauling, 1960; Grdenić, 1965). The Hg—S bond distance values are longer than in the above-mentioned mercury(II) complexes with meimt or meimtH ligands. Although the Hg atoms in these complexes have different coordination environments, the Hg—S bond values differ according to the nature of other donor atoms bound to mercury (C, Br or N). The tendency of mercury to form stronger Hg—I and weaker Hg—S bonds has been observed in the iodo complexes with other thiones, such as 3,4,5,6-tetrahydropyrimidine-2-thione (Popović et al., 2000).
The reduction in the π-electron density of the exocyclic C—S bond in the title complex relative to the average bond distance in the free ligand is accompanied by metal coordination. The extent of this reduction, as reflected in the the bond lengthening, differs between the title compound and the above-mentioned mercury complexes with meimtH. The lengthening is significant in the HgBr2(meimtH) [1.73 (2)–1.74 (2) Å; Raper et al., 1998], Hg(meimt)2 [1.747 (4) Å; Popović et al., 1999], CH3Hg(meimtH)(NO3) and CH3Hg(meimt) complexes [1.741 (8) and 1.75 (2) Å, respectively; Norris et al., 1983], while in the title complex, the C—S bonds are marginally longer than in the free ligand [S1—C11 1.698 (9) Å and S2—C21 1.721 (9) Å versus 1.682 (2) and 1.686 (2) Å]. This is a consequence of the observed tendency of mercury to form stronger Hg—I and weaker Hg—S bonds. The lengthened C—S bond is invariably associated with an increase in the double bond character of the thioamide C—N bonds (Table 1), which are slightly shortened in comparison with the values in the free ligand [1.348 (3) and 1.344((3) Å; Vampa et al., 1995]. Although the major π-electron density appears to be concentrated in the thioamide fragment, all of the ring bond distances are affected by the extended conjugation, revealing the zwitterionic character of the coordinated ligand (C═S in X2—C═S; X = any atom, 1.671 Å; Car—Nsp2 1.371 Å; Allen et al., 1987). The NH groups of the imidazole ring take part in intra- and intermolecular hydrogen bonds formation with I1 and I2 atoms (Table 2) joining molecules into endless chains parallel to the z axis.